So you mean that Personal, School and Trash are files? That would
indicate than they are standard mbox files. Maildir format doesn't work
that way. With maildir each mailbox *is* a folder, with three standard
subfolders: new (for new message), cur (for old messages), tmp (I don't
know what this is for, probably temporary storage of some kind).
And each message goes in a seperate file and they all have weird names
so that they are guaranteed to be unique, I think they use a timestamp,
the inode number, and the hostname or something like that.
Maildir has certain technical advantages, and certain not so technical
advantages. For example there is no need for locking, no rewriting of
entire mailbox, all this boosts performance and reduces risk of
corruption even in the event of a bad crash.
The performance advantages made me switch from uw-imapd to courier-imap
at work. People were getting huge attachments that crippled uw-imapd. I
think once I saw someone get a single email with 37 megs of attachments.
Bijan

OK. I misunderstood what you said in the beginning. I also don't
understand mailboxes as well as I thought I did. Time to go educate
myself :-)